Vehicle seat

ABSTRACT

To improve the seated feeling of an occupant in a seat having partially different hardness, a vehicle seat includes a seat frame, an S spring which is installed on the seat frame and receives a load of an occupant, and a seat back pad which has a plurality of regions respectively formed of different materials and is disposed between a skin material of the seat and the S spring. The S spring is disposed at a position facing a boundary portion which is provided in the seat back pad and is the plurality of regions respectively formed of different materials.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/080,864, filed Aug. 29, 2018, now U.S. Pat. No. 10,632,885, which isa National Stage Entry application of PCT Application No.PCT/JP2017/008264, filed Mar. 2, 2017, which claims the priority benefitof Japanese Patent Application No. JP 2016-041301, filed Mar. 3, 2016,the contents of each of which being incorporated herein by reference.

BACKGROUND

The present disclosure relates to a vehicle seat with seat pads havingpartially different hardness.

There is known a vehicle seat in which the hardness of a seat pad is setto be different in accordance with a portion supporting an occupant. Forexample, Japanese Patent Publication JP 4300377 B2 discloses a vehicleseat of which a side support portion is formed by a foam having hardnessdifferent at the inside and the outside of the side support portion.

SUMMARY

However, since the hardness changes largely at a boundary portionbetween different foams in the seat pad, an uncomfortable feeling isgenerated at the boundary portion and thus the seating feeling of theseat is deteriorated.

The present disclosure has been made in view of the above-describedproblem and an object of the present disclosure is to provide a vehicleseat capable of improving the seating feeling of an occupant in a seathaving partially different hardness.

The above-described problem is solved by a vehicle seat including: aseat frame; a pressure receiving member that is installed on the seatframe and receives a load of an occupant; and a seat pad which has aplurality of regions respectively formed of different materials and isdisposed between a skin material of the seat and the pressure receivingmember, wherein the pressure receiving member is disposed at a positionfacing a boundary portion of the plurality of regions.

According to the above-described vehicle seat, since the boundaryportion in a region formed of a different material in the seat pad issupported by the pressure receiving member, it is possible to reduce anuncomfortable feeling of the occupant at the boundary portion.Accordingly, it is possible to improve the seating feeling of theoccupant in a seat of which hardness is partially changed.

Further, in the above-described vehicle seat, the seat frame may be aseat back frame forming a skeleton of a seat back forming a backrestsurface, the pressure receiving member may be installed on the seat backframe in a seat width direction, the skin material may cover the seatback, the seat pad may be a seat back pad disposed between the skinmaterial and the pressure receiving member, the boundary portion may beprovided along the seat width direction, and the boundary portion mayoverlap at least a part of the pressure receiving member in an up anddown direction of the seat. With such a configuration, even when aplurality of regions formed of different materials are provided in theseat back pad disposed inside the seat back corresponding to thebackrest surface of the occupant, it is possible to reduce anuncomfortable feeling of the occupant at the boundary portion of theregions.

Further, in the above-described vehicle seat, a front end portion of theboundary portion on a front side of the seat and a rear end portion ofthe boundary portion on a rear side of the seat may be located atdifferent positions in the up and down direction of the seat. With sucha configuration, it is possible to reduce a change in hardness at theboundary portion of the regions respectively formed of differentmaterials in the seat back pad and the periphery thereof. Accordingly,it is possible to reduce an uncomfortable feeling of the occupant at theboundary portion.

Further, in the above-described vehicle seat, a connection surfacebetween the front end portion and the rear end portion may be formed ina stepped structure. With such a configuration, the hardness can bechanged stepwisely at the boundary portion and the periphery thereof.Accordingly, since it is possible to suppress an abrupt change inhardness at the boundary portion and the periphery thereof, it ispossible to reduce an uncomfortable feeling at the boundary portion.

Further, in the above-described vehicle seat, the connection surfacebetween the front end portion and the rear end portion may be formed ina gradient structure. With such a configuration, the hardness can bechanged with a gradient at the boundary portion and the peripherythereof. Accordingly, since the hardness can be changed smoothly at theboundary portion and the periphery of the boundary portion, it ispossible to reduce an uncomfortable feeling at the boundary portion.

Further, in the above-described vehicle seat, the pressure receivingmember may be set as a first pressure receiving member, the vehicle seatmay further include a second pressure receiving member that is installedon the seat back frame in the seat width direction and is provided belowthe first pressure receiving member, and one of the front end portionand the rear end portion may be located between the first pressurereceiving member and the second pressure receiving member and the otherthereof may be located at a height overlapping the first pressurereceiving member. With such a configuration, since the end portion ofthe boundary portion on the rear side of the seat in relation to the endportion thereof on the front side of the seat is strongly supported bythe pressure receiving member, the hardness is changed smoothly at theboundary portion and thus an uncomfortable feeling can be reduced.

Further, in the above-described vehicle seat, a hardness of a regionbelow the boundary portion in the seat back pad may be higher than ahardness of a region thereabove. With such a configuration, since thelower portion of the upper body of the occupant is stably supported, theposture of the occupant can be easily maintained. Further, since theupper portion of the upper body of the occupant is softly supported, aseating feeling becomes satisfactory.

Further, in the above-described vehicle seat, the seat frame may be aseat cushion frame forming a skeleton of a seat cushion forming aseating surface, the pressure receiving member may be installed on theseat cushion frame in a seat width direction, the skin material maycover the seat cushion, the seat pad may be a seat cushion pad disposedbetween the skin material and the pressure receiving member, theboundary portion may be provided along the seat width direction, and theboundary portion may overlap at least a part of the pressure receivingmember in a front to back direction of the seat. With such aconfiguration, even when a plurality of regions formed of differentmaterials are provided in the seat cushion pad disposed inside the seatcushion corresponding to the occupant seating surface, it is possible toreduce an uncomfortable feeling of the occupant at the boundary portionof the regions.

Further, in the above-described vehicle seat, a skin material suspendingportion may be attached to a groove formed in the boundary portion. Theskin material can be suspended at the position of the boundary portion.Accordingly, since the slack of the skin material at the boundaryportion is prevented, it is possible to reduce an uncomfortable feelingat the boundary portion.

Further, in the above-described vehicle seat, the boundary portion maybe a compatible portion in which the materials of the plurality ofregions are compatible. With such a configuration, it is possible towiden the load input surface at the boundary portion. Accordingly, it ispossible to reduce an uncomfortable feeling of the occupant at theboundary portion.

According to the present disclosure, it is possible to reduce anuncomfortable feeling of the occupant at the boundary portion of aregion respectively formed of different materials.

According to an aspect of the present disclosure, even when a pluralityof regions formed of different materials are provided in the seat backpad, it is possible to reduce an uncomfortable feeling of the occupantat the boundary portion of the regions.

According to an aspect of the present disclosure, it is possible toreduce a change in hardness at the boundary portion of the regionsrespectively formed of different materials and the periphery thereof.

According to an aspect of the present disclosure, an abrupt change inhardness at the boundary portion and the periphery thereof issuppressed, it is possible to reduce an uncomfortable feeling at theboundary portion.

According to an aspect of the present disclosure, since the hardnesssmoothly changes at the boundary portion and the periphery of theboundary portion, it is possible to reduce an uncomfortable feeling atthe boundary portion.

According to an aspect of the present disclosure, it is possible toreduce an uncomfortable feeling by smoothly changing the hardness at theboundary portion.

According to an aspect of the present disclosure, it is possible toeasily maintain the posture of the occupant and to obtain a satisfactoryseating feeling.

According to an aspect of the present disclosure, even when a pluralityof regions formed of different materials are provided in the seatcushion pad, it is possible to reduce an uncomfortable feeling of theoccupant at the boundary portion of the regions.

According to an aspect of the present disclosure, since the slack of theskin material at the boundary portion is prevented, it is possible toreduce an uncomfortable feeling at the boundary portion.

According to an aspect of the present disclosure, since the load inputsurface at the boundary portion is widened, it is possible to reduce anuncomfortable feeling of the occupant at the boundary portion.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments of the invention are illustrated in the drawings, inwhich:

FIG. 1 is a perspective view of a vehicle seat according to the presentembodiment;

FIG. 2 is a perspective view of a seat frame according to the presentembodiment;

FIG. 3 is a front view of a seat back pad;

FIG. 4 is a cross-sectional view taken along the line IV-IV of the seatback pad;

FIG. 5 is a cross-sectional view taken along the line V-V of the seatback pad;

FIG. 6 is a top view of a seat cushion pad;

FIG. 7 is a cross-sectional view taken along the line VII-VII of theseat cushion pad;

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of theseat cushion pad;

FIG. 9 is a cross-sectional view taken along the line V-V of a seat backpad according to a first modified example;

FIG. 10 is a cross-sectional view taken along the line V-V of a seatback pad according to a second modified example;

FIG. 11 is a cross-sectional view taken along the line V-V of a seatback pad according to a third modified example;

FIG. 12 is a cross-sectional view taken along the line V-V of a seatback pad according to a fourth modified example;

FIG. 13 is a cross-sectional view taken along the line V-V of a seatback pad according to a fifth modified example; and

FIG. 14 is a cross-sectional view taken along the line V-V of a seatback pad according to a sixth modified example.

DETAILED DESCRIPTION

Hereinafter, a vehicle seat S according to an embodiment (hereinafter,the present embodiment) of the present disclosure is described withreference to FIGS. 1 to 14. Additionally, the embodiment to be describedbelow is merely used to help the understanding of the present disclosureand does not limit the present disclosure. That is, the presentdisclosure can be modified and improved without departing from the gistthereof and the equivalents thereof are, of course, included in thepresent disclosure. Above all, an outline of each of drawings isdescribed.

FIG. 1 is a perspective view of a vehicle seat S according to thepresent embodiment and FIG. 2 is a perspective view of a seat frame Saforming a skeleton of the vehicle seat S.

FIG. 3 is a front view of a seat back pad 2 a which is a cushionmaterial of the seat back 2, FIG. 4 is a cross-sectional view takenalong the line IV-IV of the seat back pad 2 a, and FIG. 5 is across-sectional view taken along the line V-V of the seat back pad 2 a.

FIG. 6 is a top view of a seat cushion pad 1 a which is a cushionmaterial of the seat cushion 1, FIG. 7 is a cross-sectional view takenalong the line VII-VII of the seat cushion pad 1 a, and FIG. 8 is across-sectional view taken along the line VIII-VIII of the seat cushionpad 1 a.

Then, FIGS. 9 to 14 are respectively cross-sectional views taken alonglines V-V of the seat back pads 2 a according to the first to sixthmodified examples.

Configuration of Vehicle Seat S and Seat Frame Sa

First of all, configurations of the vehicle seat S and the seat frame Saaccording to the present embodiment is described with reference to FIGS.1 and 2.

The vehicle seat S of the present embodiment mainly includes, asillustrated in FIG. 1, the seat cushion 1, the seat back 2 disposed onthe upper surface side of the seat cushion 1, and a headrest 3 disposedon the upper surface side of the seat back 2. The seat frame Sa whichforms the skeleton illustrated in FIG. 2 is disposed inside the vehicleseat S.

Further, in the description below, the “front to back direction” meansthe front to back direction when viewed from a seated occupant on thevehicle seat S and means a direction aligned to the vehicle travelingdirection. The “seat width direction” means the horizontal widthdirection of the vehicle seat S and is aligned to the right and leftdirection when viewed from the seated occupant on the vehicle seat S.Further, the “up and down direction” means the height direction of thevehicle seat S and is aligned to the up and down direction when thevehicle seat S is viewed from the front side.

The seat cushion 1 is a seating portion which supports an occupant frombelow. The seat cushion 1 has a configuration in which the seat cushionpad 1 a is placed on a cushion frame 10 serving as a skeletonillustrated in FIG. 2 and the seat cushion pad 1 a is covered with askin 1 b.

The seat back 2 is a backrest portion which supports a back of theoccupant from the rear side. The seat back 2 has a configuration inwhich the seat back pad 2 a is placed on the seat back frame 20 formingthe skeleton illustrated in FIG. 2 and the seat back pad 2 a is coveredwith a skin 2 b.

The headrest 3 is a head portion which supports a head of the occupantfrom the rear side. The headrest 3 has a configuration in which aheadrest pad 3 a is placed on a pillar (not illustrated) which is a corematerial and the headrest pad 3 a is covered with a skin 3 b.

The cushion frame 10 is formed as a substantially rectangular framewhich is the skeleton of the seat cushion 1. The cushion frame 10includes, as illustrated in FIG. 2, a cushion side frame 11 which isdisposed on each of the right and left sides, a pan frame 12 which is aplate-shaped frame installed on the front upper surface of each of thecushion side frames 11, a frame connection pipe 13 which is a connectionmember installed in the vicinity of the rear end portion of each of thecushion side frames 11, and S springs 14 a and 14 b which are connectedto the substantially center portions of each of the cushion side frames11 in the front to back direction.

The S spring 14 a and the S spring 14 b are pressure receiving membersthat support the occupant sitting on the seat cushion 1 from below. TheS spring 14 a and the S spring 14 b located on the front side of theseat in relation to the S spring 14 a are respectively installed andheld on the cushion side frames 11 on both sides.

The cushion side frame 11 is formed as a sheet metal member extending inthe front to back direction. The left cushion side frame 11 and theright cushion side frame 11 are separated from each other in the rightand left direction in parallel to each other.

As illustrated in FIG. 2, a reclining mechanism 15 which rotatablyconnects the seat back 2 to the seat cushion 1 is provided between thecushion side frame 11 and the seat back frame 20.

The reclining mechanism 15 includes a connection shaft 16 which is arotation shaft of the reclining mechanism 15, a spiral spring 17 whichurges the seat back frame 20 in an upright state, and a spring lockingmember 18 that locks an extension end portion of the spiral spring 17.

The connection shaft 16 is formed as a pipe member having asubstantially circular cross-sectional shape and connecting both rightand left end portions of the cushion side frame 11 and the seat backframe 20.

The connection shaft 16 is connected while being fitted through shaftpenetration holes (not illustrated) provided at both right and leftlower end portions of the seat back frame 20 and shaft insertion holes(not illustrated) provided at both right and left rear end portions ofthe cushion side frames 11.

The spiral spring 17 is formed as a spiral wire member and is providedat the rear end portions of the right and left outer surfaces of thecushion side frames 11. One end portion of the spiral spring 17 ishooked to the spring locking member 18 to be fixed to the right and leftouter lower end portions of the seat back frame 20. The other endportion of the spiral spring 17 is fixed while being hooked to springlocking portions (not illustrated) provided on the right and left outersurfaces of the cushion side frames 11.

The spring locking member 18 is formed in a substantially L-shape bybending a sheet metal member, the upper end portion of the springlocking member 18 is fixed to the seat back frame 20, a bent portion 18a bent outward in the right and left direction is provided at the lowerend portion, and one end of the spiral spring 17 is hooked to the bentportion 18 a.

Additionally, an operation lever (not illustrated) is attached to theoutside of the cushion side frame 11. Accordingly, a mechanism isobtained in which the connection shaft 16 rotates by the operation ofthe operation lever and the seat back 2 rotates with respect to the seatcushion 1.

The seat back frame 20 is formed as a substantially rectangular frame asillustrated in FIG. 2. The seat back frame 20 includes an upper frame 21which is a hollow cylindrical body formed in a substantially invertedU-shape on the upper side, right and left side frames 22 which aredisposed to be connected to the upper frame 21 on the right and leftsides, S springs 23 a and 23 b which are installed on the substantiallycenter portions of the inner surfaces of the side frames 22, and a lowerframe 30 which is installed on the lower end portions of the innersurfaces of the side frames 22. Additionally, the side frame 22 and thelower frame 30 may be formed integrally with each other.

The right and left side frames 22 are formed in a substantially U-shapeby bending a sheet metal member inward in the right and left direction.The right and left side frames 22 extend in the up and down directionand are separated from each other in the right and left direction inparallel to each other. The right and left side frames 22 are formed togradually extend forward from the upper side to the lower side and eachside frame includes a front bent portion 22 a which is bent inward inthe right and left direction from the front end portion and a rear bentportion 22 b which is bent inward in the right and left direction fromthe rear end portion.

A concave portion 22 c which is recessed inward in the right and leftdirection is provided on the right and left inner surfaces of the rightand left side frames 22 and the concave portion 22 c has a penetrationhole penetrating in the up and down direction.

Each of the S spring 23 a and the S spring 23 b is a pressure receivingmember that supports a back and a waist of the occupant from the rearside. In the present embodiment, the pressure receiving member is formedas the metal elastic member, but the present disclosure is not limitedthereto. For example, the pressure receiving member may be formed ofresin, woven fabric, or the like and not be elastically deformed.Further, the S spring 23 a and the S spring 23 b located below the Sspring 23 a are connected to the right and left side frames 22 whileboth right and left end portions thereof are inserted and hooked to thepenetration holes of the concave portions 22 c.

The lower frame 30 is formed in a substantially U-shape by bending asheet metal member forward. The lower frame 30 includes, as illustratedin FIG. 2, a frame main body portion 31 which extends in the right andleft direction and a frame bent portion 32 which is formed by bendingboth right and left ends.

The frame bent portion 32 is disposed to be in contact with the innersurface of the side frame 22. The upper end portion of the frame bentportion 32 and the lower end portion of the side frame 22 are fixed bywelding.

The frame bent portion 32 has a shaft penetration hole (not illustrated)which is formed to penetrate in the right and left direction and theconnection shaft 16 is connected while being fitted through the shaftpenetration hole. The spring locking member 18 is fixed to the outersurface of the frame bent portion 32 by a fastening bolt 38.

As illustrated in FIG. 2, the frame main body portion 31 includes anupper end flange portion 33 a and a lower end flange portion 33 b whichprotrude forward. The upper end flange portion 33 a and the lower endflange portion 33 b are respectively provided at the upper end portionand the lower end portion of the frame main body portion 31 and extendin the right and left direction.

Next, configurations of the seat back pad 2 a and the seat cushion pad 1a is described with reference to FIGS. 3 to 8.

Configuration of Seat back Pad 2 a

First, a detail of the seat back pad 2 a is described with reference toFIGS. 3 to 5. As illustrated in FIG. 3, the seat back pad 2 a includes alower cushion region 40 which supports a lower portion of an upper bodyof the occupant, an upper cushion region 42 which supports an upperportion of the upper body of the occupant, a right cushion region 44which supports a right portion of the upper body of the occupant, and aleft cushion region 46 which supports a left portion of the upper bodyof the occupant. The above-described regions are defined by a grooveportion 48. Further, the upper surface of the upper cushion region 42has a headrest penetration hole 52 through which a pillar of theheadrest 3 is inserted. Then, a suspending wire 54 for suspending theskin 2 b on the seat front surface side is buried in the seat back pad 2a.

The lower cushion region 40 includes a first lower cushion region 40 aand a second lower cushion region 40 b which are respectively formed ofdifferent materials. A boundary between the first lower cushion region40 a and the second lower cushion region 40 b is set as a boundaryportion 41. Here, the first lower cushion region 40 a is located abovethe second lower cushion region 40 b. For example, the first lowercushion region 40 a is a lumbar support region which supports a lumbarspine of the occupant and in this case, the boundary portion 41 islocated above the lumbar support region.

Further, the first lower cushion region 40 a and the second lowercushion region 40 b may be members formed of the same material molded tohave different performances such as hardness, density, and reboundresilience at the time of foam molding, may be members respectivelyformed of the materials having different performances such as hardness,density, and rebound resilience at the time of foam molding, or may be athree-dimensional mesh-shaped elastic body or the like having adifferent structure. For example, the first lower cushion region 40 aand the second lower cushion region 40 b may be respectively molded fromdifferent synthetic resin materials such as polyurethane (PUR),polystyrene (PS), polyethylene (PE), and polypropylene (PP).

Further, both materials may be selected so that the hardness of thefirst lower cushion region 40 a is higher than the hardness of thesecond lower cushion region 40 b. As an example of this case, the firstlower cushion region 40 a may be molded by PP (polypropylene) bead foamand the second lower cushion region 40 b may be molded by polyurethanefoam. In this way, since the hardness of the first lower cushion region40 a is set to be higher than the hardness of the second lower cushionregion 40 b, the region supporting the lumbar spine of the occupant maybe set to be hard and the region supporting the upper body above thelumbar spine of the occupant may be set to be soft. Accordingly, sincethe occupant can be supported in a stable posture and the upper portionof the upper body near a shoulder of the occupant sinks into the seat, aburden is reduced and hence a seating feeling can be improved.

Additionally, the boundary portion 41 between the first lower cushionregion 40 a and the second lower cushion region 40 b is formed in a wavyshape when the seat is viewed from the front side in the exampleillustrated in FIG. 3, but the present disclosure is not limitedthereto. For example, the boundary portion may be formed in a curvedshape, a straight shape, or a complex shape (for example, a polygonalline) formed by two or more different curves and straight lines.

Further, the boundary portion 41 between the first lower cushion region40 a and the second lower cushion region 40 b may be a joint which isformed such that the first lower cushion region 40 a and the secondlower cushion region 40 b are respectively molded and are bonded to eachother by adhering. Further, the boundary portion 41 may be animpregnation layer formed when one layer penetrates the other layer atthe time of molding the second lower cushion region 40 b with the firstlower cushion region 40 a. Furthermore, the boundary portion 41 may be acompatible portion in which the molding material of the first lowercushion region 40 a and the molding material of the second lower cushionregion 40 b are mixed with each other and are hardened.

Further, as illustrated in FIGS. 3 to 5, a press felt 50 adheres to therear surfaces (the seat rear surfaces) of the first lower cushion region40 a and the second lower cushion region 40 b. The press felt 50 isdisposed at a position overlapping the boundary portion 41 in the up anddown direction of the seat. Accordingly, the strength in the peripheryof the boundary portion 41 can be improved.

Additionally, the upper cushion region 42, the right cushion region 44,and the left cushion region 46 may be molded from the same material asthat of the first lower cushion region 40 a or the second lower cushionregion 40 b or may be molded from a material different from any one ofthem.

Here, a positional relationship between the boundary portion 41 and theS springs 23 a and 23 b serving as the pressure receiving member isdescribed with reference to FIG. 5. As illustrated in FIG. 5, theboundary portion 41 and the S spring 23 a are disposed at a position atleast partially overlapping each other in the up and down direction ofthe seat. Here, a front end portion 41 a is an end portion of theboundary portion 41 on the front side of the seat and a rear end portion41 b is an end portion of the boundary portion 41 on the rear side ofthe seat. In the example illustrated in FIG. 5, the front end portion 41a and the rear end portion 41 b are disposed at the substantially sameposition in the up and down direction of the seat and both of the frontend portion 41 a and the rear end portion 41 b are disposed at aposition overlapping at least a part of the S spring 23 a in the up anddown direction of the seat.

Additionally, in the example illustrated in FIG. 5, the boundary portion41 is disposed at a position overlapping the S spring 23 a in the up anddown direction of the seat, but the boundary portion 41 may be disposedat a position overlapping the S spring 23 b in the up and down directionof the seat. Further, a different configuration example of thearrangement of the boundary portion 41 and the S springs 23 a and 23 bis described below.

As illustrated in FIG. 5, since the boundary portion 41 and the S spring23 a are disposed at a position facing each other in the up and downdirection of the seat, the boundary portion 41 that receives the load ofthe occupant can be supported by the S spring 23 a. Then, since theboundary portion 41 is a portion which changes from the hardness of thefirst lower cushion region 40 a to the hardness of the second lowercushion region 40 b, it is possible to reduce a change in hardness inthe periphery of the boundary portion 41 by supporting that portion bythe S spring 23 a as described above.

Configuration of Seat Cushion Pad 1 a

Next, a detail of the seat cushion pad 1 a is described with referenceto FIGS. 6 to 8. As illustrated in FIGS. 6 and 7, the seat cushion pad 1a includes a front cushion region 60 which supports a thigh of theoccupant, a rear cushion region 62 which supports buttocks of theoccupant, a right cushion region 64 which supports a right leg of theoccupant, and a left cushion region 66 which supports a left leg of theoccupant and each region is defined by a groove portion 68.

The front cushion region 60 includes a first front cushion region 60 aand a second front cushion region 60 b which are respectively moldedfrom different materials and a boundary between the first front cushionregion 60 a and the second front cushion region 60 b is set as aboundary portion 61. Here, the second front cushion region 60 b islocated on the front side in relation to the first front cushion region60 a. For example, the first front cushion region 60 a is an ischialtuberosity support region which supports an ischial tuberosity of theoccupant and in this case, the boundary portion 61 is located in frontof the ischial tuberosity support region.

Further, the first front cushion region 60 a and the second frontcushion region 60 b may be members formed of the same material molded tohave different performances such as hardness, density, and reboundresilience at the time of foam molding, may be members respectivelyformed of the materials having different performances such as hardness,density, and rebound resilience at the time of foam molding, or may be athree-dimensional mesh-shaped elastic body or the like having adifferent structure. For example, the first front cushion region 60 aand the second front cushion region 60 b may be respectively molded fromdifferent synthetic resin materials such as polyurethane (PUR),polystyrene (PS), polyethylene (PE), and polypropylene (PP).

Further, both materials may be selected so that the hardness of thefirst front cushion region 60 a is higher than the hardness of thesecond front cushion region 60 b. As an example of this case, the firstfront cushion region 60 a may be molded by PP (polypropylene) bead foamand the second front cushion region 60 b may be molded by polyurethanefoam. In this way, since the hardness of the first front cushion region60 a is set to be higher than the hardness of the second front cushionregion 60 b, the region supporting the ischial tuberosity of theoccupant may be set to be hard and the region supporting the front sideof the ischial tuberosity of the occupant may be set to be soft.Accordingly, since the occupant can be supported in a stable posture andthe front side of the thigh of the occupant sinks into the seat, aburden is reduced and hence a seating feeling can be improved.

Additionally, the boundary portion 61 between the first front cushionregion 60 a and the second front cushion region 60 b is formed in a wavyshape when the seat is viewed from above in the example illustrated inFIG. 6, but the present disclosure is not limited thereto. For example,the boundary portion may be formed in a curved shape, a straight shape,or a complex shape (for example, a polygonal line) formed by two or moredifferent curves and straight lines.

Further, the boundary portion 61 between the first front cushion region60 a and the second front cushion region 60 b may be a joint which isformed such that the first front cushion region 60 a and the secondfront cushion region 60 b are respectively molded and are bonded to eachother by adhering. Further, the boundary portion 61 may be animpregnation layer formed when one layer penetrates the other layer atthe time of molding the second front cushion region 60 b with the firstfront cushion region 60 a. Furthermore, the boundary portion 61 may be acompatible portion in which the molding material of the first frontcushion region 60 a and the molding material of the second front cushionregion 60 b are mixed with each other and are hardened.

Additionally, the rear cushion region 62, the right cushion region 64,and the left cushion region 66 may be molded from the same material asthat of the first front cushion region 60 a or the second front cushionregion 60 b or may be molded from a material different from any one ofthem.

Here, a positional relationship between the boundary portion 61 and theS springs 14 a and 14 b serving as the pressure receiving member isdescribed with reference to FIG. 8. As illustrated in FIG. 8, theboundary portion 61 and the S spring 14 b are disposed at a position atleast partially overlapping each other in the front to back direction ofthe seat. Here, the upper end portion 61 a is an end portion of theboundary portion 41 on the upper side of the seat and the lower endportion 61 b is an end portion of the boundary portion 61 on the lowerside of the seat. In the example illustrated in FIG. 8, the upper endportion 61 a and the lower end portion 61 b are located at thesubstantially same position in the front to back direction of the seatand both of the upper end portion 61 a and the lower end portion 61 bare disposed at a position overlapping at least a part of the S spring14 b in the front to back direction of the seat.

Additionally, in the example illustrated in FIG. 8, the boundary portion61 is disposed at a position overlapping the S spring 14 b in the frontto back direction of the seat, but the boundary portion 61 may bedisposed at a position overlapping the S spring 14 a in the front toback direction of the seat.

As illustrated in FIG. 8, since the boundary portion 61 and the S spring14 b are disposed at a position overlapping each other in the front toback direction of the seat, the boundary portion 61 that receives theload of the occupant can be supported by the S spring 14 b. Then, sincethe boundary portion 61 is a portion which changes from the hardness ofthe first front cushion region 60 a to the hardness of the second frontcushion region 60 b, it is possible to reduce a change in hardness inthe periphery of the boundary portion 61 by supporting that portion bythe S spring 14 b as described above.

Modified Examples

Next, modified examples of the seat back pad 2 a is described withreference to FIGS. 9 to 14. Additionally, in the example illustrated inFIGS. 9 to 14, the configuration of the boundary portion 41 of the seatback pad 2 a is different from that of the above-described seat back pad2 a, but the other points are common. Hereinafter, only the differentpoints is described and the common points is omitted.

FIG. 9 is a cross-sectional view taken along the line V-V of the seatback pad 2 a according to a first modified example. As illustrated inFIG. 9, in the seat back pad 2 a according to the first modifiedexample, the front end portion 41 a and the rear end portion 41 b of theboundary portion 41 are located at different heights in the up and downdirection of the seat and a connection surface between the front endportion 41 a and the rear end portion 41 b is formed as a steppedstructure. In other words, the front end portion 41 a and the rear endportion 41 b are connected to each other in a stepped (stepwise)structure. Additionally, the front end portion 41 a is located betweenthe S spring 23 a and the S spring 23 b in the up and down direction ofthe seat and the rear end portion 41 b is located at a positionoverlapping the S spring 23 a in the up and down direction of the seat.Further, the boundary portion 41 illustrated in FIG. 9 may be formed asan impregnation layer or a joint.

In this way, the boundary portion 41 is formed as a stepped structure inwhich the heights of the front end portion 41 a and the rear end portion41 b in the up and down direction of the seat are different and one endportion (in this example, the rear end portion 41 b) faces the S spring23 a. Accordingly, since a change in hardness between the boundaryportion 41 and the periphery thereof in the seat back pad 2 a isstepwise, it is possible to suppress an abrupt change in hardnessbetween the boundary portion and the periphery thereof. Accordingly, itis possible to reduce a change in hardness in the periphery of theboundary portion 41.

FIG. 10 is a cross-sectional view taken along the line V-V of the seatback pad 2 a according to a second modified example. As illustrated inFIG. 10, in the seat back pad 2 a according to the second modifiedexample, the front end portion 41 a and the rear end portion 41 b of theboundary portion 41 are located at different heights in the up and downdirection of the seat and the connection surface between the front endportion 41 a and the rear end portion 41 b forms a gradient structure.In other words, the front end portion 41 a and the rear end portion 41 bare connected to each other in a gradient structure. Additionally, thefront end portion 41 a is located between the S spring 23 a and the Sspring 23 b in the up and down direction of the seat and the rear endportion 41 b is located at a position overlapping the S spring 23 a inthe up and down direction of the seat. Further, the boundary portion 41illustrated in FIG. 10 may be formed as an impregnation layer or ajoint.

In this way, the boundary portion 41 is formed in a gradient structurein which the heights of the front end portion 41 a and the rear endportion 41 b in the up and down direction of the seat are different andone end portion (in this example, the rear end portion 41 b) faces the Sspring 23 a. Accordingly, since a change in hardness between theboundary portion 41 and the periphery thereof in the seat back pad 2 ais smooth, it is possible to suppress an abrupt change in hardnessbetween the boundary portion and the periphery thereof. Accordingly, itis possible to reduce a change in hardness in the periphery of theboundary portion 41.

FIG. 11 is a cross-sectional view taken along the line V-V of the seatback pad 2 a according to a third modified example. As illustrated inFIG. 11, in the seat back pad 2 a according to the third modifiedexample, the boundary portion 41 is formed in the same gradientstructure as that of the second modified example, but is different fromthe second modified example in the following points. That is, the thirdmodified example is different from the second modified example in that agroove portion 58 is provided in a portion of the front end portion 41 aof the boundary portion 41 and a suspending portion 59 such as asuspending wire for suspending a skin material is provided in the grooveportion 58.

In this way, also in the third modified example, similarly to the secondmodified example, the boundary portion 41 is formed in a gradientstructure in which the heights of the front end portion 41 a and therear end portion 41 b in the up and down direction of the seat aredifferent and one end portion (in this example, the rear end portion 41b) faces the S spring 23 a. Accordingly, since a change in hardnessbetween the boundary portion 41 and the periphery thereof in the seatback pad 2 a is smooth, it is possible to suppress an abrupt change inhardness between the boundary portion and the periphery thereof.Accordingly, it is possible to reduce a change in hardness in theperiphery of the boundary portion 41. Further, in the third modifiedexample, since the groove portion 58 is provided at the front side ofthe boundary portion 41 and the occupant does not contact the boundaryportion 41, it is possible to reduce the uncomfortable feeling of theoccupant at the boundary portion 41.

Additionally, in the first to third modified examples, the front endportion 41 a is disposed between the S spring 23 a and the S spring 23 band the rear end portion 41 b is disposed at a position overlapping theS spring 23 a in the up and down direction. However, the front endportion 41 a may be disposed at a position overlapping the S spring 23 aor the S spring 23 b in the up and down direction and the rear endportion 41 b may be disposed between the S spring 23 a and the S spring23 b.

FIG. 12 is a cross-sectional view taken along the line V-V of the seatback pad 2 a according to a fourth modified example. As illustrated inFIG. 12, in the seat back pad 2 a according to the fourth modifiedexample, the boundary portion 41 is formed in a structure provided withthe same groove portion 58 as that of the third modified example, but isdifferent from the third modified example in the following points. Thatis, the fourth modified example is different from the third modifiedexample in that the boundary portion 41 is formed as a compatibleportion in which the material of the first lower cushion region 40 a andthe material of the second lower cushion region 40 b are compatible.

In this way, in the fourth modified example, since the boundary portion41 faces the S spring 23 a so that a change in hardness between theboundary portion 41 and the periphery thereof in the seat back pad 2 ais smooth, it is possible to suppress an abrupt change in hardnessbetween the boundary portion and the periphery thereof. Further, sincethe load input region of the boundary portion 41 is set to be large byforming the boundary portion 41 as the compatible portion, it ispossible to reduce an uncomfortable feeling of the occupant at theboundary portion 41. Further, in the fourth modified example, the skinmaterial can be suspended in the suspending portion 59 provided in thegroove portion 58 provided at the boundary portion 41. Accordingly,since the slack of the skin material at the boundary portion 41 isprevented, an uncomfortable feeling at the boundary portion 41 can bereduced.

FIG. 13 is a cross-sectional view taken along the line V-V of the seatback pad 2 a according to a fifth modified example. As illustrated inFIG. 13, in the seat back pad 2 a according to the fifth modifiedexample, each surface excluding the rear surface (the seat rear surface)of the first lower cushion region 40 a is covered with the second lowercushion region 40 b. Then, the boundary portion 41 between the firstlower cushion region 40 a and the second lower cushion region 40 b doesnot reach the front surface of the seat back pad 2 a. In the exampleillustrated in FIG. 13, at least one of the rear end portion 41 b of theboundary portion 41 is provided at a position facing the S spring 23 a.In the example illustrated in FIG. 13, the rear end portion 41 b belowthe boundary portion 41 is located below the S spring 23 b, but the rearend portion 41 b may be provided at a position facing the S spring 23 b.

Further, in the example illustrated in FIG. 13, each surface excludingthe rear surface of the first lower cushion region 40 a is covered withthe second lower cushion region 40 b, but each surface excluding thefront surface of the first lower cushion region 40 a may be covered withthe second lower cushion region 40 b so that the boundary portion 41does not reach the rear surface of the seat back pad 2 a.

FIG. 14 is a cross-sectional view taken along the line V-V of the seatback pad 2 a according to a sixth modified example. As illustrated inFIG. 14, in the seat back pad 2 a according to the sixth modifiedexample, the front end portion 41 a of the boundary portion 41 betweenthe first lower cushion region 40 a and the second lower cushion region40 b is provided at a position facing the S spring 23 b and the rear endportion 41 b is provided at a position facing the S spring 23 a.Further, the present disclosure is not limited to the exampleillustrated in FIG. 14. The front end portion 41 a of the boundaryportion 41 may be provided at a position facing the S spring 23 a andthe rear end portion 41 b may be provided at a position facing the Sspring 23 b.

Additionally, the above-described configurations of the first to sixthmodified examples may similarly be applied to the boundary portion 61 ofthe seat cushion pad 1 a.

TABLE OF REFERENCE NUMERALS S: vehicle seat Sa: seat frame 1: seatcushion 1a: seat cushion pad 1b: skin 2: seat back 2a: seat back pad 2b:skin 3: headrest 3a: headrest pad 3b: skin 10: cushion frame 11: cushionside frame 12: pan frame 13: frame connection pipe 14a, 14b: S spring(pressure receiving member) 15: reclining mechanism 16: connection shaft17: spiral spring 18: spring locking member 18a: bent portion 20: seatback frame 21: upper frame 22: side frame 22a: front bent portion 22b:rear bent portion 22c: concave portion 23a, 23b: S spring (pressurereceiving member) 30: lower frame 31: frame main body portion 32: framebent portion 33a: upper end flange portion 33b: lower end flange portion38: fastening bolt 40: lower cushion region 40a: first lower cushionregion 40b: second lower cushion region 41: boundary portion 41a: frontend portion 41b: rear end portion 42: upper cushion region 44: rightcushion region 46: left cushion region 48: groove portion 50: press felt52: headrest penetration hole 54, 56: suspending wire 58: groove portion59: suspending portion 60: front cushion region 60a: first front cushionregion 60b: second front cushion region 61: boundary portion 61a: upperend portion 61b: lower end portion 62: rear cushion region 64: rightcushion region 66: left cushion region 68: groove portion

1-10. (canceled)
 11. A vehicle seat comprising: a seat back frame; aseat back pad that is placed on the seat back frame; and a pressurereceiving member that supports the seat back pad and extends in a seatwidth direction, wherein: the seat back pad includes a first pad portionthat is disposed at a position facing a lower end portion of thepressure receiving member and a second pad portion that is disposed at aposition facing an upper end portion of the pressure receiving member;and a hardness of the first pad portion is greater than a hardness ofthe second pad portion.
 12. A vehicle seat comprising: a seat backframe; a seat back pad that is placed on the seat back frame; and apressure receiving member that supports the seat back pad and extends ina seat width direction, wherein: the seat back pad includes a first padportion and a second pad portion, each with a hardness that is differentthan the other, and a boundary portion that is disposed between thefirst pad portion and the second pad portion; the first pad portion isdisposed below the boundary portion and the second pad portion isdisposed above the boundary portion; a lower portion of the pressurereceiving member and the first pad portion are on a same firsthorizontal plane; and an upper end portion of the pressure receivingmember and the second pad portion are on a same second horizontal plane.13. A method for manufacturing a vehicle seat, comprising: forming aseat back pad that includes a first pad portion and a second padportion, wherein a hardness of the first pad portion is greater than ahardness of the second pad portion; providing a seat back frame;attaching a pressure receiving member that extends in a seat widthdirection to the seat back frame; and placing the seat back pad on theseat back frame so that the first pad portion faces a lower end portionof the pressure receiving member and the second pad portion faces anupper end portion of the pressure receiving member.